The manufacture of a product requiring multiple manufacturing steps has, in the past, been conveniently performed by batch manufacturing processes. In batch processing, each process step is completed for every member of a group before the group is transferred to the next station for further processing.
The manufacture of modern ophthalmic lenses provides an example in which batch methods, for the most part, are no longer the most efficient means of production. However, some steps in the production of ophthalmic lenses still may be most efficiently handled by batch manufacturing processes. For example, lenses that are coated often require curing to harden and fix the coating, and all of the coated lenses must go through the same curing process regardless of their particular prescription.
Furthermore, ophthalmic lenses are made of polymer materials the melting point of which may be close to the temperature at which the coatings are cured. Thus, the lenses may become relatively soft during the curing process making it desirable to keep the environment in which the lenses are cured free of particulate contaminates that may come into contact with and adhere to the soft surfaces of the lens. It is also desirable that the curing environment be maintained at a substantially uniform temperature throughout, so that the lenses are exposed to the required temperature for the required time necessary to effect the complete curing of the coating material.
Therefore, a need exists for processes and equipment for use in batch curing coated lenses. Additionally, a need exists for processes and equipment in which the curing is carried out free from particulates and in carried out at a substantially uniform temperature.